Joseph Carl Kumaradas

Joseph Carl Kumaradas
Ryerson University · Department of Physics

PhD

About

50
Publications
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748
Citations

Publications

Publications (50)
Article
Purpose A real-time and non-invasive thermometry technique is essential in thermal therapies to monitor and control the treatment. Ultrasound is an attractive thermometry modality due to its relatively high sensitivity to change in temperature and fast data acquisition and processing capabilities. A temperature-sensitive acoustic parameter is requi...
Article
Full-text available
Objective: This work aims to determine whether photoacoustic (PA) thermometry from a commercially available PA imaging system can be used to control the temperature in nanoparticle-mediated thermal therapies. Methods: The PA imaging system was interfaced to obtain PA images while scanning ex-vivo tissue. These images were then used to obtain tem...
Article
Full-text available
In this study, we present facile fabrication of a miniaturized remote sensing SERS platform using highly tunable Nano-Sphere Lithography (NSL) technique. Using 200 μm diameter optical fibers with high numerical aperture (0.5NA), the SERS enhancement of remote sensing was found to be 98% of direct sensing configuration. Standard silica optical fiber...
Conference Paper
Raman spectroscopy (RS) can provide a molecular vibrational fingerprint of an analyte. In this study, RS was used to distinguish normal tissues from tumor tissues using ex-vivo and deparaffinized breast tissues.
Article
Full-text available
Plasmonic gold nanorods (AuNRs) coated with four different thickness silver shells (AuNR\Ags) were synthesized and tested for their efficiency in Surface Enhanced Raman Scattering (SERS) signal enhancement for biomedical applications. Both AuNRs and AuNR\Ags were prepared using a modified seed-mediated method and then characterized using TEM, XPS a...
Article
Synthetic aperture focusing techniques (SAFT) mathematically synthesize an effective large aperture by scanning a single-element transducer to improve the lateral spatial resolution and extend the depth of field. In this work, two frequency-domain SAFT algorithms are proposed, which are based on the synthetic aperture radar’s wavenumber algorithm....
Article
Full-text available
Our group has recently developed a finite element model of a nanoparticle-mediated optical breakdown phenomena. Previously, this model was used to analyze the role of the nanoparticle morphology and the wavelength dependence of a nanoparticle-mediated optical breakdown threshold during near-infrared ps and fs pulse exposures. In this study, we prov...
Article
Full-text available
This paper investigates the wavelength dependence of the threshold of gold nanorod-mediated optical breakdown during picosecond and femtosecond near infrared optical pulses. It was found that the wavelength dependence in the picosecond regime is governed solely by the changes of a nanorod's optical properties. On the other hand, the optical breakdo...
Data
Theory and parameters used in the model.
Conference Paper
The resolution of conventional single-element ultrasound imaging varies spatially and depends on several factors, such as the central frequency, bandwidth, and the transducer’s active aperture size. Synthetic aperture focusing techniques (SAFT) enable dynamic focusing, which, among others, could lead to improvements in the spatial resolution of ult...
Article
Full-text available
This paper presents a theoretical study of a 6 ps laser pulse interaction with uncoupled and plasmon coupled gold nanoparticles. We show how the one-dimensional assembly of particles affects the optical breakdown threshold of its surroundings. For this purpose we used a fully coupled electromagnetic, thermodynamic and plasma dynamics model for a la...
Article
In this paper, we perform a finite element (FE)-based numerical analysis to calculate the photoacoustic (PA) signal generated by spherical gold-silver (Au-Ag) alloy nanoparticles (NPs). These spherical particles are size-controlled and monodispersed, with tunable plasmonic resonance wavelength via change of the alloy composition. This enables their...
Conference Paper
We have collected Raman spectral libraries for obtaining operator independent diagnostics under ex-vivo and in-vivo conditions and we have tested this approach using multivariate analysis on known solutions with Raman active components. Article not available.
Conference Paper
Full-text available
Photoacoustic (PA) imaging has matured into a clinical modality for tissue imaging and functional cancer cell research. It uses a pulsed laser to irradiate a region and generate a thermally-induced acoustic pressure wave that can be collected by an ultrasound transducer. The optical absorption/PA contrast of the region of interest can be enhanced b...
Conference Paper
Full-text available
Tremendous progress is being made in the integration of nanoparticles into micro-analytical systems for biosensing. These materials are shown to enhance the analyte capture capability of biosensing platforms. We have implemented a computational model that considers the sensor’s geometry, size, analyte concentration and type to predict the number of...
Article
Full-text available
Evidence suggests that compression and shear wave elastography are sensitive to the mechanical property changes occuring in dying cells following chemotherapy, and can hence be used to monitor cancer treatment response. A qualitative and quantitative understanding of the mechanical changes at the cellular level would allow to better infer how these...
Article
Gold nanorods (GNRs) are being exploited for their absorption properties to improve thermal therapy. However, a key challenge is delivering sufficient concentration of GNRs to induce a therapeutic effect. In this study, ultrasound and microbubbles (USMBs) were used to enhance intracellular uptake of GNRs. AML-5 cells in suspension (0.6 mL) were exp...
Article
The flow characterization of blood through healthy and diseased flow geometries is of interest to researchers and clinicians alike, as it may allow for early detection, and monitoring, of cardiovascular disease. In this paper, we use a numerically efficient particle-based flow model called multiparticle collision dynamics (MPC for short) to study t...
Conference Paper
Full-text available
The optical scattering and absorption of gold nanorods (GNRs) depends on its size, shape, and surroundings. This dependence is due to both intrinsic and extrinsic effects. A good understanding of this dependence is needed for applications of GNRs in photo-thermal therapy, optical and opto-acoustic imaging, biosensing, and other photonic areas. Extr...
Article
Full-text available
Surface modes of spherical objects subject to ultrasound excitation have been recently proposed to explain experimental measurements of scattering from microspheres and ultrasound contrast agents (UCAs). In this work, the relationship between surface modes and resonance frequencies of microspheres and UCAs is investigated. A finite-element model, b...
Article
The effects of the dielectric environment on the optical extinction spectra of gold nanorods were quantitatively studied using individual bare and silica-coated nanorods. The dispersion and amplitude of their extinction cross-section, dominated by absorption for the investigated sizes, were measured using spatial modulation spectroscopy (SMS). The...
Article
Full-text available
The measurement of the ultrasound backscatter from individual micron-sized objects such as cells is required for various applications such as tissue characterization. However, performing such a measurement remains a challenge. For example, the presence of air bubbles in a suspension of cells during the measurements may lead to the incorrect interpr...
Conference Paper
Full-text available
The measurement of the ultrasound backscatter from individual micron-sized objects is required to gain an understanding of the behavior of both weak (cells) and strong (contrast agents) scatterers for applications ranging from tissue characterization to molecular imaging. However, obtaining such a response remains a challenge. For instance, the pre...
Article
Full-text available
The high frequency backscatter from cells with a nucleus to cell volume ratio of 0.50 cannot be adequately modeled as a homogeneous sphere. It was hypothesized that the cytoplasm of such cells is of fluid nature. This work attempts to model the ultrasound backscatter (10-62 MHz) from some non-nucleated biological specimens. This was done by measuri...
Article
The use of heat producing GNRs to augment the dosing of chemotherapeutic agents in cultured mammalian cells was investigated. Hexadecyltrimethylammonium bromide was purchased from Fluka. GNRs were synthesized using standard protocols detailed in a previous publication, with reference to the Murphy and Liz-Marzán groups. GNRs were synthesized by com...
Article
A study was conducted to investigate the high frequency acoustic backscatter response from non-nucleated biological specimens. The study used sea urchin oocytes to prepare sparse suspension in artificial seawater at room temperature. A VisualSonics VS40B ultrasound imaging devices was used during the study for data acquisition with transducers. The...
Article
High-frequency ultrasound is a novel method to detect cell death based on changes in cell morphology that cause alterations in the acoustic properties of cell ensembles in tissues. In previous work, our group has suggested that for cells with a nucleus to cell volume ratio of 0.33, the backscatter response from single cells was best modeled as a fl...
Article
A finite?element model of wave propagation using COMSOL Multiphysics (COMSOL Inc., Burlington, MA) was developed to solve the problem of high?frequency ultrasound (10?70 MHz) scattering from spheres. This model is being used to predict ultrasound backscatter from cells for ultrasound tissue characterization. In this work, backscatter from an elasti...
Conference Paper
It has been shown that high-frequency ultrasound (20 MHz-60 MHz) can be used to detect structural and physical changes in tissues and cell ensembles during cell death. However, the changes observed are not well understood. Recent theoretical models treating the cell as a homogeneous sphere did not show good agreement with experimental data. We have...
Conference Paper
The modeling and control of laser-irradiated tissue is a challenging problem due to the non-linear behavior of the tissue when heated. This is compounded by the fact that in-vivo tissue parameters are not well known. In order to properly model and design control methods for LITT, it is necessary to quantify the uncertainties in the model parameters...
Article
A finite element model (FEM) of acoustic wave propagation through 3-D arbitrary-shaped structures is developed to solve the problem of high frequency acoustic scattering. The FEMLAB® software package was used to develop and solve acoustic scattering models from fluid, rigid, and elastic spheres immersed in a fluid medium, for which analytical solut...
Article
Several three-dimensional hyperthermia treatment planning systems for deep regional hyperthermia have been successfully utilized for improving the performance of applicators such as the BSD Sigma 60. Treatment planning systems for superficial heating in contrast have been less utilized. This paper presents a study of the applicability of the finite...
Article
Thermal therapy is an experimental treatment to destroy solid tumours by heating them to temperatures ranging from 55 degrees C to 90 degrees C, inducing thermal coagulation and necrosis of the tumour. We are investigating the feasibility of interstitial microwave thermal therapy as a salvage treatment for prostate cancer patients with local recurr...
Article
Temperature inhomogeneity in hyperthermia treatments often limits the total thermal dose that can be delivered to the tumour region. To reduce such inhomogeneities, a prototype dynamically modifiable square array of saline-filled patches which attenuate microwave energy was developed for superficial treatments that use external microwave applicator...
Article
Hyperthermia has been shown to improve local tumour control of superficial and deep seated lesions when combined with radiotherapy. There remains difficulty in heating larger tumours with conventional applicators, but this is being addressed by several new applicator designs. This paper presents a new numerical model of microwave heating which is d...
Article
Heating of superficial tumours with microwave waveguide applicators has been shown in phase III trials to significantly improve the local control of small lesions when combined with radiation therapy. This success has not yet translated to the treatment of larger tumours, due to difficulty in adequately heating the entire tumour region. Several mod...
Conference Paper
Phase 3 clinical trials have demonstrated the efficacy of hyperthermia as an adjuvant to radiotherapy for the treatment of small superficial tumours. Adequate heating of larger tumours however remains a technically challenging problem due to the inhomogeneous nature of tissue properties in large tumours. A dynamic bolus attachment for external sing...
Article
Full-text available
Relatively mild temperatures (40-41.5 degrees C) can sensitize human cells to radiation without the development of thermal tolerance to radiosensitization. Therefore there may be a therapeutic benefit to adding mild hyperthermia to brachytherapy regimens for the treatment of cancer. However, the required heating times are long (approximately 48 h)...
Article
Detection of radiotherapy field misalignments with electronic portal imaging devices requires the precise initial registration of the digital portal image with a reference image indicating the prescribed field alignment. Moreover, for real-time continuous detection this registration must be performed rapidly--arguably within 250 ms. The quality of...
Article
The effectiveness of hyperthermia treatments is often limited by temperature inhomogeneity that arises in the treatment field due to variable tissue properties and blood flow. Moreover, blood flow can change during a treatment, leading to the formation of hot and cool areas even if the initial temperature distribution is uniform. A variable microwa...
Article
A model to characterize the performance of 810 nm InGaAsP high power fabry-perot B laser was developed and applied. The model determines the effect of operating temperature on various emission characteristics and reliability of the above laser. The computer simulations along with the experimental results determined that laser has a threshold curren...
Article
Full-text available
A finite-element model of wave propagation using COMSOL Multiphysics has been developed to solve the problem of ultrasound scattering from spherical structures. This model will be used to predict ultrasound backscatter from cells for ultrasound tissue characterization, and scattering from microbubble contrast agents. In this paper, we discuss an im...
Article
Full-text available
A finite-element model of wave propagation using COMSOL Multiphysics (COMSOL Inc., Burlington, MA) was developed to solve the problem of high frequency ultrasound scattering from spheres. This model is used to predict ultrasound backscatter from cells for ultrasound tissue characterization. In this work, the backscatter from an elastic sphere was u...

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Projects (2)
Project
Surface-enhanced Raman spectroscopy
Archived project
Validation of theoretical framework of gold nanoparticle-mediated optical breakdown